The fix-and-follow method may be helpful when examining infants and toddlers. Photo: Getty Images.

Assessing visual function in infants can be challenging. Fix-and-follow is a common simple method for assessing early development of visual perception in this patient population; however, there is no formal reproducible method for grading its capacity. Researchers recently modified the fix-and-follow grading scale for easy application in preverbal children, and it proved reliable and reproducible in clinic.

In this cross-sectional study, the fix-and-follow method was evaluated in 21 consecutive preverbal children. Fixation was categorized as grade 1 if there was no response to the target and grade 2 if there was a response but only for <3 seconds. Grades of 3 and 4 were assigned based on a child’s capacity to fixate on a moving target for ≥3 seconds and shift fixation from one target to another. If only one of these two criteria was met, grade 3 was assigned. If both were met, grade 4 was assigned. Smooth pursuit movement was also evaluated, where grade 1 indicated no movement, grade 2 was partial movement and grade 3 was complete movement.

Two ophthalmologists independently applied the grading method in all patients. Then one of the two examiners repeated the examinations to determine the repeatability of the grading system. The intra-observer agreement was excellent (Kappa coefficient=0.823), and the inter-observer agreement was good (Kappa coefficient=0.625).

“Our new fix-and-follow grading system exhibited high repeatability and reproducibility in infants and children, who often do not have the capacity to cooperate with an examiner,” the study authors concluded in their paper. “It could be useful for both screening and longitudinal follow-up of visual function in preverbal children and easily applied in practice.” They warned, however, that grading and interpretation should be conducted carefully in patients with ocular motility disorders.